Variable frequency control module for an AC compressor in an air conditioning system

ABSTRACT

A variable frequency control module includes a temperature detecting unit outputting a detecting signal corresponding to ambient temperature detected thereby, an operating unit operable so as to output an input signal corresponding to a target temperature, and a processing unit receiving the detecting signal and the input signal from the temperature detecting unit and the operating unit., and outputting a control signal corresponding to a difference between the ambient temperature and the target temperature based on the detecting signal and the input signal. An encoding unit receives the control signal from the processing unit, encodes the control signal into an encoded signal, and outputs the encoded signal to a frequency converting unit that outputs a driving signal having a frequency corresponding to the encoded signal to an AC compressor so that an AC compressor is operated at a rotary speed based on the driving signal.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority to Taiwanese Application No. 096140366, filed Oct. 26, 2007, the disclosure of which is herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a variable frequency control module, more particularly to a variable frequency control module for an AC compressor in an air conditioning system.

2. Description of the Related Art

Referring to FIG. 1, a conventional air conditioner 1 is shown to include a temperature detector 12 for detecting ambient temperature, an operating unit 13 operable so as to set a target temperature, and a processor 11 coupled to the temperature detector 12 and the operating unit 13 for controlling a rotary speed of a compressor 14 based on the ambient temperature detected by the temperature detector 12 and the target temperature set by the operating unit 13. In operation, when the ambient temperature detected by the temperature detector 12 is higher than the target temperature, the processor 11 activates the compressor 14 to operate at a constant rotary speed until the ambient temperature detected by the temperature detector 12 decreases to a first temperature lower than the target temperature Thereafter, the processor 11 deactivates the compressor 14 until the ambient temperature detected by the temperature detector 12 rises to a second temperature higher than the target temperature.

In such a configuration, since the ambient temperature varies frequently between the first and second temperatures, a relatively large difference between the first and second temperatures makes a user feel uncomfortable. Furthermore, during transition between deactivation and activation of the compressor 14, the rotary speed of the compressor 14 rapidly increases or decreases, thereby generating noise and resulting in increased power consumption.

To overcome discomfort caused by large temperature variation, a conventional variable frequency air conditioner has been proposed, wherein a DC compressor is controlled by a frequency converter using voltage-controlled modulation such that a rotary speed of the DC compressor changes with variation of a duty cycle of a voltage signal supplied to the DC compressor. However, such a frequency converter cannot be applied to an AC compressor suitable for high-power output.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a variable frequency control module for an AC compressor in an air conditioning system that can overcome the aforesaid drawbacks of the prior art.

According to the present invention, there is provided a variable frequency control module for controlling an AC compressor in an air conditioning system. The variable frequency control module comprises:

a temperature detecting unit adapted for detecting ambient temperature, and outputting a detecting signal corresponding to the ambient temperature detected thereby;

an operating unit operable so as to output an input signal corresponding to a target temperature;

a processing unit coupled to the temperature detecting unit and the operating unit for receiving the detecting signal and the input signal therefrom, and outputting a control signal corresponding to a difference between the ambient temperature and the target temperature based on the detecting signal and the input signal;

an encoding unit coupled to the processing unit for receiving the control signal therefrom, encoding the control signal into an encoded signal, and outputting the encoded signal; and

a frequency converting unit coupled to the encoding unit for receiving the encoded signal therefrom, generating a driving signal having a frequency corresponding to the encoded signal from the encoding unit, and adapted to output the driving signal to the AC compressor so that the AC compressor is operated at a rotary speed based on the driving signal from the frequency converting unit.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings, of which:

FIG. 1 is a schematic circuit block diagram of a conventional air conditioner;

FIG. 2 is a schematic circuit block diagram illustrating the first preferred embodiment of a variable frequency control module for an AC compressor in an air conditioning system according to the present invention; and

FIG. 3 is a schematic circuit block diagram illustrating the second preferred embodiment of a variable frequency control module for an AC compressor in an air conditioning system according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before the present invention is described in greater detail, it should be noted that like elements are denoted by the same reference numerals throughout the disclosure.

Referring to FIG. 2, the first preferred embodiment of a variable frequency control module 2 for controlling an AC compressor 15, such as a three-phase AC compressor, in an air conditioning system according to the present invention is shown to include a temperature detecting unit 21, an operating unit 22, a processing unit 23, an encoding unit 24, a frequency converting unit 25, and a display unit 26.

The temperature detecting unit 21 is adapted for detecting ambient temperature, and outputs a detecting signal corresponding to the ambient temperature detected thereby.

The operating unit 22 is operable so as to output an input signal corresponding to a target temperature.

The processing unit 23 is coupled to the temperature detecting unit 21 and the operating unit 22 for receiving the detecting signal and the input signal therefrom, and outputs a control signal corresponding to a difference between the ambient temperature and the target temperature based on the detecting signal and the input signal.

The encoding unit 24 is coupled to the processing unit 23 for receiving the control signal therefrom, encodes the control signal into an encoded signal, and outputs the encoded signal. In this embodiment, the encoding unit 24 includes a plurality of switches 241 that are coupled between the processing unit 23 and the frequency converting unit 25 and that are controlled by the control signal from the processing unit 23, thereby generating the encoded signal.

The frequency converting unit 25 is coupled to the encoding unit 24 for receiving the encoded signal therefrom, generates a driving signal having a frequency corresponding to the encoded signal from the encoding unit 24, and is adapted to output the driving signal to the AC compressor 15 so that the AC compressor 15 is operated at a rotary speed based on the driving signal from the frequency converting unit 25.

The display unit 26 is coupled to the processing unit 23 for displaying the ambient temperature. In this embodiment, the display unit 26 includes a seven-segment display.

In this embodiment, the processing unit 23 can be configured by a software program so that the rotary speed of the AC compressor 15 is graded with the difference between the ambient temperature and the target temperature. For example, when the difference between the ambient temperature and the target temperature is greater than 10° C., the rotary speed of the AC compressor 15 is controlled at a first rotary speed (S1). When the difference between the ambient temperature and the target temperature ranges from 8° C. to 10° C., the rotary speed of the AC compressor 15 is controlled at a second rotary speed (S2). When the difference between the ambient temperature and the target temperature ranges from 6° C. to 8° C., the rotary speed of the AC compressor 15 is controlled at a third rotary speed (S3). When the difference between the ambient temperature and the target temperature ranges from 4° C. to 6° C., the rotary speed of the AC compressor 15 is controlled at a fourth rotary speed (S4). When the difference between the ambient temperature and the target temperature ranges from 2° C. to 4° C., the rotary speed of the AC compressor 15 is controlled at a fifth rotary speed (S5). When the difference between the ambient temperature and the target temperature ranges from −1° C. to 2° C., the rotary speed of the AC compressor 15 is controlled at a sixth rotary speed (S6). In this example, S1>S2>S3>S4>S5>S6. It is noted that, when the difference between the ambient temperature and the target temperature is equal to −1° C., the rotary speed of the AC compressor 15 is controlled to be zero, i.e., the AC compressor 15 is deactivated. As a result, it is possible to maintain the difference between the ambient temperature and the target temperature to a range from −1° C. to 1° C. through the control signal.

FIG. 3 illustrates the second preferred embodiment of a variable frequency control module 2′ for controlling an AC compressor 15 according to this invention, which is a modification of the first preferred embodiment. In this embodiment, the operating unit 22′ includes a plurality of used-operated switches 221. The display unit 26′ includes a liquid crystal display panel 261 for displaying the ambient temperature thereon, and a set of indicating lamps 262 for indicating information pertinent to the rotary speed of the AC compressor 15.

The following are some of the advantages attributed to the variable frequency control module 2,2′ of the present invention:

1. During activation of the AC compressor 15, the rotary speed of the AC compressor 15 gradually increases or decreases, thereby minimizing noise and resulting in decreased power consumption.

2. When the ambient temperature is approximate to the target temperature, the rotary speed of the AC compressor 15 is a relatively lowest rotary speed, i.e., the sixth rotary speed (S6) in the aforesaid example, and the difference between the ambient temperature and the target temperature can be constantly maintained within a desired narrow range. Therefore, constant temperature control can be achieved.

While the present invention has been described in connection with what are considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements. 

1. A variable frequency control module for controlling an AC compressor in an air conditioning system, said variable frequency control module comprising: a temperature detecting unit adapted for detecting ambient temperature, and outputting a detecting signal corresponding to the ambient temperature detected thereby; an operating unit operable so as to output an input signal corresponding to a target temperature; a processing unit coupled to said temperature detecting unit and said operating unit for receiving the detecting signal and the input signal therefrom, and outputting a control signal corresponding to a difference between the ambient temperature and the target temperature based on the detecting signal and the input signal; an encoding unit coupled to said processing unit for receiving the control signal therefrom, encoding the control signal into an encoded signal, and outputting the encoded signal; and a frequency converting unit coupled to said encoding unit for receiving the encoded signal therefrom, generating a driving signal having a frequency corresponding to the encoded signal from said encoding unit, and adapted to output the driving signal to the AC compressor so that the AC compressor is operated at a rotary speed based on the driving signal from said frequency converting unit.
 2. The variable frequency control module as claimed in claim 1, wherein said encoding unit includes a plurality of switches coupled between said processing unit and said frequency converting unit.
 3. The variable frequency control module as claimed in claim 1, further comprising a display unit coupled to said processing unit for displaying the ambient temperature.
 4. The variable frequency control module as claimed in claim 3, wherein said display unit includes a seven-segment display.
 5. The variable frequency control module as claimed in claim 3, wherein said display unit further indicates information pertinent to the rotary speed of the AC compressor.
 6. The variable frequency control module as claimed in claim 5, wherein said display unit includes a liquid crystal display panel for displaying the ambient temperature thereon, and a set of indicating lamps for indicating the information pertinent to the rotary speed of the AC compressor.
 7. The variable frequency control module as claimed in claim 1, wherein said operating unit includes a plurality of user-operated switches. 